java计时中字符串时间与秒的转换

public static int timeToSec(String instr) {
String[] a = instr.split("\\.");
String[] b = a[0].split(":");
return Integer.valueOf(b[0]) * 60 * 60 + Integer.valueOf(b[1]) * 60
+ Integer.valueOf(b[2]);
}
public static String unitFormat(int i) {
String retStr = null;
if (i >= 0 && i < 10)
retStr = "0" + Integer.toString(i);
else
retStr = "" + i;
return retStr;
}
public static String secToTime(int time) {
String timeStr = null;
int hour = 0;
int minute = 0;
int second = 0;
if (time <= 0)
return "00:00";
else {
minute = time / 60;
if (minute < 60) {
second = time % 60;
timeStr = unitFormat(minute) + ":" + unitFormat(second);
} else {
hour = minute / 60;
if (hour > 99)
return "99:59:59";
minute = minute % 60;
second = time - hour * 3600 - minute * 60;
timeStr = unitFormat(hour) + ":" + unitFormat(minute) + ":" + unitFormat(second);
}
}
return timeStr;
}
public static void test(){
int t = timeToSec("02:33:10");
System.out.println(t);
System.out.println(secToTime(t));
}